How can I transform origin when I am in Edit Mode with shortcut?
here are some thing to get you started.
Shift + Tab for switching Snapping on/off
Shift + Ctrl + Tab for switching between Snapping options/methods
Transforming origin -  So you are asking for transforming origins, probably so that you can move/scale/rotate at that origin. But Blender has a more elaborate method to do so, by using 3d Cursor. Its a just a null pointer made for this purpose. Simply being in edit mode press Shift + S and you will find options to change the 3d Cursor location like this -

Also you can select some loops and snap the 3d Cursor using same method Shit+S. Still only the Cursor position will change, else nothing is going to change. Now press &quot;.&quot; near right Shift on keyboard for this menu and you will have to select 3d Cursor , now things will move/scale/rotate from this point/3D cursor/Temporary origin. -

Also please enable Pie menu from the preferences -  ITS A GREAT TIME SAVER !